mwalsh wrote:I may change out to some street tires when these are worn out, but for now I like the fatter tires for precisely the reason GRA points out - burning more calories!
Just depends on what you enjoy. Personally, I find riding off-road tires on pavement so much less pleasant than street tires that I'm less motivated to ride, and so do less of it. Right now, I've got an 'all-terrain' tire on the rear, because that's what the bike had when I bought it (used), and the slick on the front (replaced the other A-T tire when I had a blowout on that). I find this combo provides more than adequate grip and control for the occasional dirt trail (not steep single-track), without giving me the noise and vibration that I hate from a full knobby. Once the rear wears out I'll replace it with another slick, as I rarely ride dirt - I prefer hiking on trails where a mountain bike would be appropriate, although if I were riding in someplace like southern Utah my druthers would be different.
As to safety, I've been riding and commuting in heavy street traffic since I was nine or so, and I guess I'm inured to the danger, but I keep a very close eye on traffic (especially since I can't hear it coming now, as I ride without my hearing aids), and ride defensively, making use of hand signals, making eye contact, and generally riding very predictably while not putting myself in situations that are risky. OTOH, distracted/inattentive drivers have become a much greater risk since the advent of cell phones, and especially smart phones.
I started riding a lot at a time ('70s) when John Forester's "Vehicular Cycling" was the done thing (see https://en.wikipedia.org/wiki/Vehicular_cycling), and while that's been mostly discredited as a way to get mass ridership, there are times when 'taking the lane' is entirely appropriate. At night I'm wearing a neon-green reflective vest plus two rear blinkies, one blinking headlight, plus side, front, rear and pedal reflectors. I find that constant-on lights are too hard to see against the background of urban light pollution, especially when coming up a line of cars between them and the curb where they're unlikely to be looking in any case. Learned that lesson after a guy right-hooked me while I had my headlight constant-on, but I saw him start to crank his wheel and yelled before he could move too far, so he only sideswiped me a little.
I don't need a headlight strong enough to light up the street as it's plenty bright to see the road in the typical city, just one that allows me to be seen. I've also used head-mounted lights at times so I can shine it directly at a driver, but don't use one at the moment.
Fortunately, the Bay Area has a strong cycling community and there are many cities here with good cycling infrastructure, although mine lags a bit when it comes to things like parking-protected bike lanes, and either those or separate bike paths are what's needed to get large numbers of riders other than fit young males (or fitter older males like me who've been doing it since we were young males) riding. Still, we do have bike lanes and some marked bike streets/boulevards.